The present invention generally relates to a spray head for an inline mixer for mixing multiple components of a combined fluid stream.
Inline mixing of combined fluid streams, including fluid streams of different viscosities, may be useful in a wide variety of settings including the medical field. In one example of an application in the medical field, inline mixing of two or more combined fluid streams is employed to form a sealant, such as a tissue sealant, that is applied to human and animal tissue. Such sealant may be employed to seal or repair tissue at a surgical or wound site, to stop bleeding, seal wounds, treat burns or skin grafts and a variety of other purposes.
In the medical field, and more particularly in the field of tissue sealants used to seal or repair biological tissue, such sealant is typically formed from two or more components that, when mixed, form a sealant having sufficient adhesion for a desired application, such as to seal or repair skin or other tissue. Such sealant components are preferably biocompatible, and can be absorbed by the body, or are otherwise harmless to the body, so that they do not require later removal. For example, fibrin is a well known tissue sealant that is made from a combination of at least two primary components—fibrinogen and thrombin, which have, depending on the temperature, different viscosities of about 300 cps and 15 cps, respectively. Upon coming into contact with each other, the fibrinogen and thrombin components interact to form a tissue sealant, fibrin, which is extremely viscous.
Sealant components may be kept in separate containers and are combined prior to application. However, because sealant components such as fibrinogen and thrombin have different viscosities, complete and thorough mixing is often difficult to achieve. If the components are inadequately mixed, then the efficacy of the sealant to seal or bind tissue at the working surface is compromised.
To overcome the difficulties of the formation of the highly viscous fibrin in the medical field, in providing tissue sealant, it has become common to provide inline mixing of two or more components—in lieu of batch or tank mixing of the components—to form a tissue sealant, just prior to its application on a work surface. Some sealant products that may provide suitable mixtures include FLOSEAL, COSEAL, TISSEEL and ARTISS sealants from Baxter Healthcare Corporation, OMINEX sealants from Johnson & Johnson and BIOGLUE sealants from Cryolife, Inc. Such sealant may be applied by a dispenser that ejects sealant directly onto the tissue or other substrate or working surface. Examples of tissue sealant dispensers are shown in U.S. Pat. Nos. 4,631,055, 4,846,405, 5,116,315, 5,582,596, 5,605,255, 5,665,067, 5,989,215, 6,461,361 and 6,585,696, 6,620,125, 6,802,822, PCT Publication No. WO 96/39212, and US Pat. Appl. Pub. 2009/0038701, all of which are incorporated herein by reference. Further examples of such dispensers also are sold under the Tissomat™ and Duploject™ trademarks, which are marketed by Baxter AG. Typically, in these devices, two individual streams of the components fibrinogen and thrombin are combined and the combined stream is dispensed to the work surface. Combining the streams of fibrinogen and thrombin initiates the reaction that results in the formation of the fibrin sealant. While thorough mixing is important to promote fibrin formation, fouling or clogging of the dispenser tip by the formation of fibrin prior to dispensing can interfere with proper functioning of the dispenser. Such clogging or fouling may result from contact or mixing of the sealant components in a dispenser and maintaining the mixture in the dispenser for an extended period of time prior to ejection of the mixture from the dispensing tip.
In current mixing systems, the quality of mixing of two or more components having different viscosities may vary depending on the flow rate. For example, under certain flow conditions, the components may be dispensed as a less than thoroughly mixed stream. Accordingly, there is a desire to provide a mixing system which is not dependent on the flow rate to achieve sufficient mixing.
Although prior devices have functioned to various degrees in forming and dispensing mixtures, there is a continuing need to provide a mixer and dispensing system that provides reliable and thorough mixing of at least two components (such as, for example, for a tissue sealant) for application to a desired work surface or other use applications in other fields. Such a mixing system could be provided to dispense the mixture just prior to or at least in close proximity to its intended use or application. Preferably, such a mixer and dispensing system would also mix the components and rapidly dispensing the mixture from the system without allowing internal low flow or stagnant zones to form and thereby avoid undue fouling or clogging of the dispenser.
In addition, the medical procedure may require an interruption in the dispensing. Should the interruption be extended, fibrin will form in any mixture that resides in the dispensing tip, which will likely lead to clogging of the tip. Therefore, after such an interruption the dispensing tip should be able to be easily replaced with a new tip to allow the dispensing to resume.